Temporal resolution of CW fNIRS devices

1 min read

This is a guest post by Ning Liu from Stanford University.

Temporal resolution provides information on the distance of time between the acquisitions of two images (data) of the same area. It is the reciprocal of sampling rate (or acquisition rate) of an fNIRS device. For some devices, sampling rate is a fixed number; for some other ones, sampling rate may depend on number of sources or detectors to use. Why is that? It is because they have different instrumental design. For those with unfixed sampling rate, multiple sources time-share an optical detector by means of a multiplexing circuit that turns the sources on and off in sequence, so that only one source within the detector range is on at any given time. The NIRx system, for instance, are using this type of design. For those with fixed sampling rate, they usually use low frequency modulated light source to provide the excitation light, thus one detector can ‘see’ only one source.

For instance, Hitachi ETG4000 system has sampling rate of 10Hz (from http://www.hitachi.com/businesses/healthcare/products-support/opt/etg4000/contents2.html), thus its temporal resolution is 100ms. Some other device, such as NIRScout, has sampling rate from 2.5 – 62.5 Hz (from https://nirx.net/nirscout/), thus its temporal resolution is 16 – 400ms. Why the sampling rate is changing from 2.5 – 62.5 Hz? That’s because users can choose different number of sources and detectors in their configuration. The more number of sources and detectors to use, the smaller the sampling rate. The following table is from a review article (Scholkmann, et al., 2014) on NeuroImaging volume 85 (2104), a special issue of functional near-infrared spectroscopy. It summarizes the specifications of some popular commercially available fNIRS devices, mainly focused on continuous wave devices.

Time resolution of NIRS devices
Time resolution of NIRS devices (click to enlarge, F. Scholkmann et al. / NeuroImage 85 (2014) 6–27)

本文作者为斯坦福大学刘宁。她提供NIRS培训服务。



写作助手,把中式英语变成专业英文


Want to receive new post notification? 有新文章通知我

第五十四期fNIRS Journal Club通知2024/07/27, 10am 黄鑫

电子烟作为一种新型的尼古丁输送装置,常以安全健康、有助于戒烟的形象出现在公众视野中,使得大批消费者转而投入到此类产品的怀抱中。然而,相关研究却仍存较大短板,深入了解电子烟对行为与脑功能活动的影响将更好
Wanling Zhu
10 sec read

第五十三期fNIRS Journal Club视频 李洪

Youtube: https://youtu.be/czyJTrXhees优酷:https://v.youku.com/v_show/id_XNjQwNjc5OTk0OA==.html 个体在处理不同
Wanling Zhu
12 sec read

第五十三期fNIRS Journal Club通知2024/06/22, 10am 李洪

个体在处理不同记忆负荷信息时会表现出一定的行为差异。作为一项新兴指标,瞬时脑信号变异性能够揭示个体内部因任务需求不断变化而进行的神经资源分配,从而为了解大脑如何适应和处理不同复杂程度的信息提供了新的见
Wanling Zhu
8 sec read

One Reply to “Temporal resolution of CW fNIRS devices”

  1. Hello Ning and Xu,

    Great read, thanks for this!

    Just wanted to let you know that the NIRScout has been extended to 100hz max sampling rate with the newest version of NIRStar 15-2, so the typical range for sampling with that system would then be roughly ~4-100hz, depending on the source illumination multiplexing sequence.

    Keep up the great work!

    Sincerely,

    Thomas Johannsen
    NIRx Medical Technologies

Leave a Reply

Your email address will not be published. Required fields are marked *